Eggs have been vilified for many years by well-meaning health practitioners for their high cholesterol content. The message to limit eggs to lower heart disease risk has been widely circulated and the ‘dietary cholesterol equals blood cholesterol’ view is a standard of popular lay dietary recommendations. Few though consider whether the evidence now justifies such restrictions.
Dietary cholesterol only has a small impact on blood cholesterol
Over 50 years of research in this area suggests that dietary cholesterol only has a weak effect on plasma cholesterol concentrations. In contrast, trans fats and saturated fat in our diet have a far stronger effect on the amount of cholesterol in our blood, and on risk of heart disease, than the cholesterol we get from eating cholesterol-containing foods like eggs.
Today, we recognise that dietary effects on blood cholesterol levels should be viewed from both the effect foods have on ‘bad’ LDL cholesterol (that can cause fatty material to build up in artery walls), as well as on ‘good’ HDL cholesterol. The ratio of LDL:HDL cholesterol is important in heart disease risk; the risk is particularly high if you have a high level of bad cholesterol and a low level of good cholesterol.
Cholesterol feeding studies demonstrate that dietary cholesterol increases both LDL and HDL cholesterol with little change in the LDL:HDL ratio. Reviews of these studies report that the addition of 100mg cholesterol per day to the diet increases total cholesterol with a 1.9 mg/dL increase in LDL cholesterol and a 0.4 mg/dL increase in HDL cholesterol. On average, the LDL:HDL ratio change per 100 mg/day change in dietary cholesterol is from 2.60 to 2.61, which would be predicted to have little effect on heart disease risk. These data may help to explain population studies showing that dietary cholesterol is not related to coronary heart disease incidence or mortality across or within populations.
Eating cholesterol-containing foods within a healthy balanced diet is acceptable for most of the population
So consuming eggs and other foods that are high in cholesterol such as prawns and offal for most people doesn’t seem to have as great an effect on blood cholesterol levels compared to eating a diet high in saturated fat. These foods, in the general population, are therefore not notably restricted in general healthy eating advice, and can be included as part of a healthy, balanced and varied diet.
However, there are some groups that may be more at risk from dietary cholesterol in foods. Heart UK recommends that people with familial hypercholesterolaemia, a genetic condition that affects blood cholesterol, only eat modest amounts of foods containing cholesterol. A sensible amount is described as no more than three or four eggs a week, and shellfish no more than once or twice a week, but to avoid offal altogether.
Limited research has also suggested that there may be a small but positive association between egg consumption and heart risk in people with diabetes. This needs to be replicated in further studies for any firm conclusions to be drawn, and a recent Australian study in type 2 diabetic patients found no such association.
And what about service users? For an older residential care population, breakfast can be a mealtime where the person is the most alert and have the best appetite, so a cooked breakfast with eggs could be good to include.
Like most other things, eggs can be enjoyed, but everything in moderation.
